Comparative immuno-reactivity of recombinant non-structural protein 2 fragments (N- and C- terminus) to detect bluetongue viral antibodies in small ruminant serum samples

• Published in: Small ruminant research Vol. 172; pp. 8 - 15
• Main Authors: Chacko, Nirmal, Biswas, Sanchay Kumar, Mohanty, Nihar Nalini, Chand, Karam, Pandey, Awadh Bihari, Mondal, Bimalendu, Shivachandra, Sathish Bhadravati
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01-03-2019
• Subjects: Antibodies; Bluetongue virus; Indirect-ELISA; N- and C- terminus; Recombinant non-structural protein 2; Small ruminant serum; Antibodies; Small ruminant serum; Indirect-ELISA; Recombinant non-structural protein 2; N- and C- terminus; Bluetongue virus
• ISSN: 0921-4488; 1879-0941
• DOI: 10.1016/j.smallrumres.2019.01.006

•Production of recombinant non-structural protein 2 fragments of BTV; rNS2Nt and rNS2Ct.•Evaluation of diagnostic efficacies of rNS2Nt and rNS2Ct fusion proteins in ELISA format.•Detection of bluetongue viral NS2 specific antibodies in ruminant serum samples.•rNS2 N-terminus protein indicated better immuno-reactivity than rNS2 C-terminus protein.
Bluetongue viral antibody detection assays are important for routine disease diagnosis and sero-surveillance in susceptible host’s especially small ruminants. In the present study, a partial NS2 gene encoding for two non-structural protein-2 fragments; N-terminus (1M-A177 aa) and C-terminus (178P-V354 aa) of BTV-23, were cloned separately, expressed and purified as recombinant NS2Nt and NS2Ct fusion proteins (˜39 kDa each) from prokaryotic expression system (Escherichia coli). Subsequent to affinity chromatographic purification under non-denaturing condition, both rNS2Nt and rNS2Ct fusion proteins were obtained in sufficient quantity and quality. Further, both antigens were also found to possess good reactivity in detecting NS2 specific BTV antibodies irrespective of serotypes in ruminant serum samples by indirect-ELISA. Of two fragments, rNS2Nt was found to be more efficient as diagnostic candidate. However, in comparison to structural protein based VP7 c-ELISA and rVP7 i-ELISA, the sensitivity (5.1%, 8.2%) and specificity (2.5%, 3.2%) of rNS2Nt i-ELISA were found to be relatively lower, respectively. The study indicated that N-terminus of NS2 protein could be used either alone or in combination/fusion with other non-structural proteins (NS1/NS3) of BTV for potential utility of NS protein based indirect-ELISA as an alternate assay for routine sero-surveillance of BTV infection in ruminants.